Engine fuel injection timing device



Sept. 17, 1968 MCDOWELL ET AL 3,401,679

ENGINE FUEL INJECTION TIMING DEVICE Filed July 21, 1966 PT B INVENTORS ROBERT D. A IcDOWELL RALPH 7566 JR. GLENN I. BRANSTAD +2 7- a MATTORNEYS United States Patent 3,401,679 ENGINE FUEL INJECTION TIMING DEVICE Robert D. McDowell, Ralph Tegg, Jr., and Glenn I. Branstad, Peoria, 111., assignors to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed July 21, 1966, Ser. No. 566,980 4 Claims. (Cl. 123-139) ABSTRACT OF THE DISCLOSURE A device for automatic timing of fuel injection in a turbocharged internal combustion engine wherein the timing is varied in accordance with engine requirements and particularly to means for varying the timing in response to turbocharged intake manifold pressure.

Automatic timing has been accomplished, for example, in such devices as that shown in the patent to Backlund et al., 2,977,778, wherein the timing is varied in accordance with engine speed. It has been found that engine speed is not always entirely satisfactory as an indication of desired timing, particularly where the engine is employed in a relatively fast-moving vehicle such as a truck as compared to track-type tractors and the like. There are instances where a relatively constant speed may be accompanied by an abrupt reduction in load. For example, when a truck passes over the crest of a hill it may maintain or even slightly increase speed, but the reduced load experienced in downhill travel indicates a requirement for retarding fuel injection timing and this would not be properly reflected by a speed sensitive device.

Accordingly, it is an object of the present invention to provide a device for varying fuel injection timing which is directly responsive to engine manifold pressure and, therefore, reflects a combination of load and speed rather than speed only. Further and more specific objects and advantages of the invention are made apparent in the following specification wherein reference is made to the accompanying drawing illustrating a preferred form of the invention and one modification thereof.

In the drawing:

FIG. 1 is a sectional view through an injection timing device and a portion of the fuel injection mechanism of a typical compression ignition engine and showing schematically a connection from the engine intake manitold with the device of the invention;

FIG. 2 is a sectional view taken on the line IIII of FIG. 1 for illustrating a construction detail; and

FIG. 3 is a view of a portion of the mechanism illustrated in FIG. 1 and showing a modification thereof.

Referring first to FIG. 1, a typical fuel pump generally indicated at and one such pump is provided for each cylinder of the engine. The pumps are driven in timed sequence by cams, one of which is shown at 11, on a camshaft 12. The camshaft is driven by a gear 14, which in turn is driven by a gear, a portion of which is shown at 15, being one of the gears of a conventional timing gear train. The gear 14 is held against longitudinal movement on the shaft 12 by a key device shown at 16, registering in a groove 17 in the hub of the gear. The gear 14 is not directly connected with shaft 12 but is connected through a coupling 18 having a part 19 extending into a central opening 20 in the gear hub and keyed against rotation therein by a flat such as best shown at 21 in FIG. 2. The coupling 18 is connected with the gear 14 by a helical splined connection represented at 22 so that movement of the coupling axially toward and away from the camshaft will produce indexing of the camshaft relative to the gear 14 and, therefore, advancing or retracting of the timed injection caused by the cams 11. Advance in timing is effected automatically upon increased pressure in the engine intake manifold which is represented at 24 as receiving air from a turbocharging device represented at 25. Increase in pressure within the manifold 24, resulting from a combination of high speed and load, will be transmitted through a conduit 26 to a chamber 28, closed by a flexible diaphragm 29. A diaphragm cup 30, acting in the manner of a piston, movable with respect to the chamber 28, has a threaded connection with a plunger 31 which is slidable in a bore of a cover plate 32 for the chamber and held against rotation therein by a pin and slot arrangement 34. At its inner end, the plunger passes through a wall 35 and engages the coupler member 18. A head 36 on the plunger is held in a recess in the coupler by a plate 37 so that reciprocal motion of the plunger will be transmitted to the coupling. A spring 38 interposed between the wall 35 and diaphragm cup 30 tends to retract the piston and may, if desired, be balanced by a lighter spring 39 for the purpose of making the piston sensitive to slight variations in pressure. Lubricating oil is fed into the chamber containing the spline 22 as through a conduit 40 and a suitable drain 41 permits escape of air and any oil possibly entrapped in the chamber between the wall 35 and cup 30. With the construction described, the indexing of the cam 11 and precise timing of fuel injection is varied automatically in response to pressure in the intake manifold which, as previously described, reflects speed and load rather than the speed only.

A modified form of the invention employs oil under pressure for moving the coupling member and indexing the camshaft rather than the direct mechanical connection aflorded by the plunger 31. Such a modification is shown in FIG. 3 wherein primed numbers are used for corresponding parts. In this figure, the plunger shown at 31' is in effect a valve spool operated by a sliding piston of suitable plastic material illustrated at 29' and corresponding to the diaphragm of FIG. 1. In this modification, pressure entering through the conduit 26' urges the piston toward the left as viewed in FIG. 3 against the force of spring 38 and causes a groove 44 in plunger 31' to register simultaneously with a passage 45 and a passage 46. Consequently, oil under pressure from a suitable source entering from a line 47 is communicated to a. chamber 48 and acts against the coupler 18' which now serves in the manner of a piston to urge it toward the left and through the splined connection 22', effecting indexing of the camshaft. A spring 49 tends to return the coupler when the pressure is reduced and when reduced pressure behind piston 29 permits return of plunger 31', pressure in chamber 48 escapes through passages 50 and 51 and thence through space provided by a loose fit between the member 18 (see FIG. 2) and the camshaft 12.

We claim:

1. An automatic timing device for a turbocharged internal combustion engine having a rotatable camshaft as a part of the engine timing mechanism, a rotatable member for driving said shaft, a helically splined coupling between said member and shaft whereby axial movement of the coupling will radially adjust the timing shaft, and means responsive solely to engine speed and load as reflected by engine intake manifold pressure for imparting such axial movement to the coupling.

2. The combination of claim 1 in which the means operates in response to pressure in the engine intake manifold. I

3. The combination of claim 2 in which pressure actuated plunger means engages the coupling, and means communicating the interior of the intake manifold with said plunger means.

4. The combination of claim 2 including a source of pressure to move the coupling, a valve controlling said pressure, and means responsive to engine manifold pressure for opening and closing said valve.

References Cited UNITED STATES PATENTS Eideneier 123-140 Eideneier 123-140 Camner 123-140 Isley 123-140 Deutschmann 123-139 10 LAURENCE M. GOODRIDGE, Primary Examiner. 

